Orchards are perennial cultures, and, especially in organic fruit production, it is essential to design and manage orchards in a way which favours predators and parasitoids over pests. Increasing plant biodiversity and habitats in such a way that beneficial organisms are favoured is called Functional Agrobiodiversity (FAB). The value of FAB for reducing pesticide use in fruit production is generally acknowledged, and many organic fruit growers try to increase it in spite of a shortage of information on FAB, economical and technical challenges and lack of situation-specific, detailed advice. To improve this situation, ECOORCHARD combined several complementary approaches and prioritizes making information and tools about FAB available to practitioners.

Flower strips increase plant diversity in orchards

We have installed several field trials in seven partnering countries (Belgium, Switzerland, Denmark, Germany, Italy, Poland, and Sweden), to analyse the impact on natural pest control in relation to the botanical resources (with and without flower strips).

The flower strips that fulfil our functional-agro biodiversity (FAB) criteria contain up to 30 perennial forb species, supplemented by eight grass species, in order to meet the following criteria for implementing flower strips in the alleyways of apple orchards:

attractive to the natural enemies in focus,

not attractive to pest insects and voles,

flowering sequentially throughout the crop season,

short growing with small rosettes to tolerate repeated mulching,

tolerant to machine traffic

bi-annual to perennial,

tolerant to nutrient rich orchard soil conditions,

competitive to other weeds and

tolerant to shady lighting conditions.

In our 3-year investigation period, we found clear evidence that flower strips can significantly increase the plant diversity in orchards. In particular, the number of species and ground cover by FAB plants and herbs in general, which are important for the promotion of agrobiodiversity, have increased. The selected plant species are shown to be suitable for use in apple orchards throughout Europe.

More natural enemies on the apple trees

We found that the frequency and timing of mulching flower strips must be carefully aligned with the stage of development of beneficial arthropods so that they will not be physically harmed and their habitat and food resources will not be destroyed. Our entomological studies show that on a wide continental scale the use of perennial flower strips in the alleyways of apple tree rows increase the presence of natural enemies on the trees. This increase leads to higher control of key apple pests and a reduction in fruit damage. Although pest suppression and damage reduction may not be enough to use this conservation biological control strategy as a stand-alone practise, flower strips can contribute to building the resilience of the apple agroecosystem against pests, reducing the need for insecticide use and favouring conservation.

Obstacles for on-farm implementation

However, we found that the availability of regional seed mixtures is a bottleneck for on-farm implementation as it is not guaranteed in various European countries. Further possible obstacles are missing adapted machinery on-farm, and availability of native seed mixtures (ecotypes). However, new mulching devices have been developed during the last years which are best adapted to manage orchard understorey sparing flower strips and making it possible to adapt mulching heights.

Handbook on FAB assessment

Methods for farmers and advisors self-assessment of FAB services in orchards were selected based on performance criteria (time, materials and skill needed, information provided), and demonstrated in workshops/ on farm and a by a practical handbook on FAB assessment (available in 7 languages). In 2016 and 2017, 40 and 50 farmers tested at least one method each and the handbook was improved by experiences collected, and has proved a valuable tool in communicating FAB to growers and advisors.

The handbook includes a registration sheet with illustrations of important predators and can be used to learn to familiarize oneself with the beneficial insects for the orchard throughout the year, and to record the effects of management practices on important groups of beneficial organisms such as spiders, earwigs, syrphids, ladybirds, etc. The handbook and videos about FAB can be accessed on The European Biodiversity Orchard-Network at http://ebionetwork.julius-kuehn.de/, where other information on FAB is also available, as well as on Organic Eprints.

Technical guide on how to manage FAB

A technical guide on FAB management has just been published, and made available in 8 languages. This is a very important outcome, which shares experiences and advice on how to maintain and manage orchard FAB with information and very useful illustrations about orchards, flowers and beneficial insects and their interactions. The guideline is free to download on https://shop.fibl.org, organic e-prints and ebion-network.